[R] non-linear model parameterization

Irene Mantzouni ima at difres.dk
Mon Oct 1 03:52:19 CEST 2007

Dear all,
I would like to fit a non-linear model of the form:
with nls().
However this model is somehow overparameterized and I get the error message about
singular gradient matrix at initial parameter estimates.
What I am interested in is to make inference about parameters b and g, so this has to be taken into account in the model formulation. 
What options do I have?
Also, how is it possible to fit a partially linear model? 
Thank you!!
Irene Mantzouni
PhD student

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